I hope that a Doctor 'chimes' in here on this.
Any time you have sudden changes to your breast, like overnight swelling, warmth of the breast and no temperature, something that resembles a bug bite but won't go away with creams/or antibiotics, needs to be seen immediately by a breast specialist. Ruling out the worst case scenario and finding only an infection, is the best route.
I notice in the posts on this site that many women have had these symptoms and I don't see any "professionals" stating the above. I'm not trying to scare anyone, but Inflammatory Breast Cancer (IBC) presents exactly like the above. And time is not on your side if that is what it is. If one course of antibiotics do not resolve the issue, find a physician who is familiar with IBC, and have them RULE IT OUT!
This discussion is related to Lymph node involvment